feat(subscription): gate insurance pages behind "insurance" plan feature

Wrap InsurancePricingPage and ClaimsPage in <FeatureGate feature="insurance">
so direct-URL access is blocked without an active subscription that enables
the feature. Add feature: "insurance" to the sidebar links (doctor/clinic/
secretary sections) so the menu items hide when the plan lacks it.

Make AdminSubscriptionPage feature controls dynamic: derive the plan feature
checkboxes from FEATURE_LABELS (now including "insurance") and switch the Zod
schema to z.record, so adding a feature only touches the label map.

No backend/migration change: plan.features is free-form JSON; existing plans
default to insurance:false and admins enable it per plan.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

assets/admin/components/layout/Sidebar.tsx

@@ -197,11 +197,13 @@ function buildSections(
                         to: "/admin/insurance-pricing",
                         icon: ShieldCheckIcon,
                         label: "قیمت‌گذاری بیمه",
+                        feature: "insurance",
                     },
                     {
                         to: "/admin/claims",
                         icon: DocumentTextIcon,
                         label: "مطالبات بیمه",
+                        feature: "insurance",
                     },
                     { to: "/admin/staff", icon: UserPlusIcon, label: "پرسنل" },
                     {
@@ -276,11 +278,13 @@ function buildSections(
                         to: "/admin/insurance-pricing",
                         icon: ShieldCheckIcon,
                         label: "قیمت‌گذاری بیمه",
+                        feature: "insurance",
                     },
                     {
                         to: "/admin/claims",
                         icon: DocumentTextIcon,
                         label: "مطالبات بیمه",
+                        feature: "insurance",
                     },
                     { to: "/admin/staff", icon: UserPlusIcon, label: "پرسنل" },
                     {
@@ -345,11 +349,13 @@ function buildSections(
                         to: "/admin/insurance-pricing",
                         icon: ShieldCheckIcon,
                         label: "قیمت‌گذاری بیمه",
+                        feature: "insurance",
                     },
                     {
                         to: "/admin/claims",
                         icon: DocumentTextIcon,
                         label: "مطالبات بیمه",
+                        feature: "insurance",
                     },
                 ],
             },